Hello Judy,
Thank you for your reply.
Please ignore the first reply that I made. We don't have the error message anymore, but just have the divergence issue.

We have an inlet in the liquid phase and an outlet in the gas phase. Feed gas (as bubbles) introduces via the inlet, reacts, and generate byproducts.
The byproducts and remaining feed gas are transferred from the liquid phase to the gas phase, and finally go out through the outlet.
Our electrode rotates (using "moving wall"), and therefore the electrolyte (the liquid phase) is stirred. The temperature is almost maintained constant (room temperature). Initially, the liquid phase contains water with a very low amount of an ion, and the gas phase is nitrogen.

For the first step, we switched our inlet and outlet to walls and will switch back later on. Thus, we are starting with simple reactions without inlets and outlet. We will definitely add more reactions. I've attached screenshots. If you need further information, please feel free to ask me.

Thank you for your time and help.